A variable displacement compressor and a displacement control valve for use in such compressors, varies the displacement of the compressor by closing or opening a control path between a discharge chamber or a suction chamber and a crank chamber. The insert members are formed in mutually a same shape. The second node and third node share a temporal key. 4 \u03bcm and an average area density of NbC precipitates of 60% or less of that of the central portion of the ferrite grains is formed along grain boundaries of the ferrite grains, for example, the steel sheet consisting of 0. At least one nanoparticle is provided on the projecting feature between the first and second electrodes. The IrOx nanostructures can be partially coated with an electrical insulator, such as SiO2, SiN, TiO2, or spin on glass, leaving the IrOx distal ends exposed.